Russian k75 capacitors
- Thread starter Fitnessed
- Start date
les24preludes
pfm Member
For coupling caps I would use the teflon FT-2. They are the only caps I use for coupling. Rated 200V but seem to be good for a lot more. FT-3 are rated higher but are larger.
les24preludes
pfm Member
FT-2 - don't hesitate!
les24preludes
pfm Member
Have you directly compared K73-16 to FT-2? I don't know the K73s. Any comments on sound quality?
Yes. I've about 50 boxes of Soviet caps & resistors
The teflons take forever to come good and have a 'liquidity' to them (they sound like Teflon caps sound), they mask the smaller details and for me the K73-16 is the one.
K73 are cheap and they are extremely transparent / non existant, if you think they reveal a 'hardness' then I'm afraid that's the resistors.... YMMV, etc
This really depends on what you want to achieve. Do you want to get the best out of the amp, or do you want it to sound exactly like a factory amp? I believe @Mike P found the K40Y-9 to be the closest sonically to the originals
You might find it more of a struggle to get the axial lytic caps
les24preludes
pfm Member
I can't comment on K73-16. I compared the FT-2s to several polypropylene caps and to the green Russian PIOs. The FT-2s were considerably more detailed and neutral, as you would expect from a teflon cap. I also preferred them to polystyrene and silver mica. I've not had a problem with burn-in with teflon caps.
Useful info
"I find that the relative permitivity or dielectric constant is often a fair guide to a material's "goodness" for use in an audio capacitor":
Vacuum 1 (by definition)
Air 1.0006
PTFE 2.1
Polypropylene 2.2-2.36
Polystyrene 2.4-2.7
PETP 3
Polyimide 3.4
Paper (unoiled) 3.5
Transformer Oil 4
Mica 3-6
Glass 5-10
Tony L
Administrator
Interesting discussion. I just went with K40-Y9 and carbon film Takman resistors as that seemed the consensus at the time. Very happy with that decision, and all the Russian military caps seem to last forever too. I can’t recall any discussion of failures with them. I do have a little stash I’m keeping should I need them (enough to fully rebuild my pair of TL12 Plus again), but I doubt that will occur.
This prompted me to have a peep at the English Acoustics site to see what they are using these days. Looks like K40-Y9 for the 0.22uF, and maybe for the 0.1uF, though I can’t see the markings and both seem to have a clear heatshrink. Resistors look to be mainly metal film, which wouldn’t be my choice. I get the impression from far too much obsessive reading that carbon comps sound the best, but have issues, carbon film seem the sensible compromise, and metal film shifts the sound a bit too modern/lean/bright.
This is just not something I’d ever be prepared to rip out and replace to test/second-guess, so I just went with a consensus view. I read miles of old Japanese sites, looked at Classique Sounds, ancient Yahoo groups etc. My goal was only to restore and make safe and reliable, not to alter the sound. My aim was at how a new one would have sounded in 1958 or whenever, though I’ve still no real idea by how far and in what specific way sonically I’ll have missed that mark.
This prompted me to have a peep at the English Acoustics site to see what they are using these days. Looks like K40-Y9 for the 0.22uF, and maybe for the 0.1uF, though I can’t see the markings and both seem to have a clear heatshrink. Resistors look to be mainly metal film, which wouldn’t be my choice. I get the impression from far too much obsessive reading that carbon comps sound the best, but have issues, carbon film seem the sensible compromise, and metal film shifts the sound a bit too modern/lean/bright.
This is just not something I’d ever be prepared to rip out and replace to test/second-guess, so I just went with a consensus view. I read miles of old Japanese sites, looked at Classique Sounds, ancient Yahoo groups etc. My goal was only to restore and make safe and reliable, not to alter the sound. My aim was at how a new one would have sounded in 1958 or whenever, though I’ve still no real idea by how far and in what specific way sonically I’ll have missed that mark.
I suppose whichever way I go the components involved should in theory be superior and tighter toleranced than the available ones back in the day.
Struggling to decide which way metal film carbon film, improvement reliability etc route or a bit more period looking.
As with radford amps I have seen modern components used and various technicians work on modern equivalents.
In analysis paralysis with it all…
Really appreciate everyone’s input
Struggling to decide which way metal film carbon film, improvement reliability etc route or a bit more period looking.
As with radford amps I have seen modern components used and various technicians work on modern equivalents.
In analysis paralysis with it all…
Really appreciate everyone’s input
Resistors were mainly out.
Caps were out but potentially could be reformed,just want it all spot on and done tbh.
Have stripped resistors and caps and are all safely removed and bagged,if someone wants to go back...
Just which rd to go down is difficult as i tend to look at the originality side and also the technician measuring route....
TonyScarlett
pfm Member
If I could have got K40s for a reasonable price I would have definitely used them in mine, K42s still not cheap but a reasonable compromise in my book. People who have heard both seem to report no difference in sound between them.
Re the Resistors, got to be carbon film all the way, metal film just look wrong in an ST20.
TS
Re the Resistors, got to be carbon film all the way, metal film just look wrong in an ST20.
TS
Tony L
Administrator
Another thing to bear in mind with resistors, especially metal film, is they will likely be too short to span the tags. 1 Watt Takman carbon films reach the widest span in the amp, which is one reason I went for them in both my builds. Extending resistor leads looks crap and adds a lot of work!
Tarzan
pfm Member
I use these in a Tripath amplifier and they are as smooth as silk, full and big sounding- l know this as l have more or less another identical amplifier with the same value Clarity Caps and they sound quite a bit different, to recap the K75 will certainly help tame any brightness you may have in the system.